Switch construction



April 1, 1947. E. A. LINK 2,418,359

SWITCH CONSTRUCTION Filed May 8, 1943 3 Sheets-Sheet 1 J5 2%.? w 24 Z319 w 20" 5 7 \T 1/2 i j 2 2/ J 1/ 32 I {1% INVEN TOR. mum A l/lvxr ATTONEY.

APril 1947- E. A. LINK 2,418,359

SWITCH CONSTRUCTION Filed May 8, 1945 3 Sheets-Sheet 2 Z3 Z7 Z6 Z5 24/ za; 6

i I INVENTOR 32 f3 [am/1 [/l/A 37, :TIQLIII ATTORNEY- April 1, 1947. E.A. LINK 2,413,359

SWITCH CONSTRUCTION Filed May 8, 1943 s Sheets-Sheet 5 14 TTORNE KPatented Apr. 1, 1947 UNITED STATES PATENT OFFICE SWITCH CONSTRUCTIONEdwin A. Link, South Milwaukee, Wis., aesignor to Line Material Company,South Milwaukee} Wis., a corporation oi Delaware.

Application May 8, 1943, Serial No. 488,140

11 Claims. (Cl. 200-116) This invention relates to a switchconstruction.

In greater detail, this invention relates primarily to a switchconstruction of the circuit breaker type.

Objects of this invention are to provide a circuit breaker which has aquick make and a quick break, which has condition responsive means ofthe trip type, which is so constructed that it releases the circuitbreaker so that the circuit breaker will open under predeterminedconditions, and which is provided with a handle or other operating meansfor normally opening and closing the circuit breaker and for resettingthe trip means, the trip means and the operating means being so relatedthat the trip means will operate to release the circuit breakerirrespective of the position of the operating means and irrespective ofany motion that the operating means may be executing at the time thetrip means operates so that the trip means is trip free and will operateno matter whether the operating means is forcibly held in closedposition or is being moved from one position to another.

Further objects are to provide a circuit breaker which is so constructedthat the circuit breaker cannot be closed until the trip means has movedback to normal position, and in which the resetting of the trip means isaccomplished by moving the operating means towards open position, suchmotion being followed by movement .to closed position after theresetting of the trip means when it is desired to again close thecircuit breaker after the occurrence of the predetermined condition.

Further objects are to provide a construction in which the trip meansmay be either thermo statically or magnetically or otherwise operatedand which has either a quick action or a delayed action and which isadjustable so that the condition to which it will respond may bepredetermined.

Further objects are to provide a circuit breaker in which the mechanismis so arranged that it is easy to operate in opening and closing thecircuit breaker and in resetting the trip means, and which is so madethat there is no great wear on the parts during the opening and closingof the circuit breaker or during the resetting oi. the trip means as themechanism is so arranged that during resetting, for example, relativelysmall forces or pressures are exerted between the cooperating parts,thereby minimizing wear.

Further objects are to provide a circuit breaker in which the trip meansis required to exert only 2 a very small i'orce in order to causeautomatic operation, the relation of the parts insuring relatchingwithout any chance of wedging or jamming either the .trip mechanism as awhole or any portion of the latch means,

Further objects are to provide a circuit breaker having switch operatingmeans which in turn is operated through the agency of an actuatorpivotally mounted on a carrier, and to provide main operating means fornormally rocking an over center spring attached at one end to theactuator back and forth across the pivot point of the actuator to causethe opening and closing of the circuit breaker and to so relate theparts of the circuit breaker that the carrier will rock the pivot pointof the actuator across the center line of the spring means to causeopening of the circuit breaker directly by the pivotal rocking motion ofthe actuato when the carrier is released by a condition responsive meanswhich normally restrains the carrier against motion, and to have thespring means coact with the actuator in such a manner that the actuatorconstitutes a bell crank lever which urges the carrier towards openposition when the circuit breaker is in closed position without allowingthe direct pull of the spring means to bias the actuator, and to soorganize the parts that in both manual opening and closing motion and inautomatic opening motion the rocking motion of the actuator itselfcauses a quick operation of the circuit breaker, the same actuatoracting in its capacity as an actuator both for manual opening andclosing and for automatic opening of the circuit breaker.

In greater detail, further objects are to provide a circuit breaker asset forth above in which the carrier pivotally carries the actuator andin which the spring means is connected to the actuator at an oil'setpoint so that the actuator acts in the manner of a bell crank lever tourge the carrie towards released position with a force whose value maybe accurately predetermined and is only a very small fraction of thetotal pull of the spring means.

Further objects are to provide a circuit breaker construction which issturdy and is reliable in operation, which may be installed in atransformer case and submerged in the oil in the transformer case ifdesired, and which if a thermostatic trip means is employed, may bearranged to have the thermostatic means respond solely to the heatgenerated by current passing through the thermostatic means or to thecombined action of the heat in the oil from the 2,41e,aso

transformer or other device as well as from the heat due to the currentpassing through the thermostatic means, or may be arranged to respondsolely to the heat of the oil.

Embodiments of the invention are shown in the accompanying drawings, inwhich:

Figure 1 is a vertical sectional view through the circuit breakershowing the circuit breaker in closed position.

Figure 2 is a view corresponding to Figure 1 showing the circuit breakermanually opened.

Figure 3 is a view corresponding to Figure 1 showing the circuit breakerautomatically opened.

Figure 4 is a plan view "of the circuit breaker with parts sectionedoff.

Figure 5 is a sectional view on the line H of Figure 1.

Figure 6 is a view showing the circuit breaker mounted within atransformer casing.

Figure 7 is a sectional view on the line |l of Figure 6.

Figure 8 is a view of a further form of mounting for the circuitbreaker.

Figure 9 is a wiring diagram.

Figure 10 is a view, partly in section, of a further form of conditionresponsive means.

Before proceeding with the detailed description of this invention it isto be understood that the circuit breaker may have either a singleswitch means or a plurality of switch means, a circuit breaker with asingle switch means having been chosen for the sake of illustration.

Referring to the drawings, it will be seen that the circuit breakercomprises a stationary contact l and a movable contact 2. The stationarycontact may be in the form of a plunger provided with a shoulder at itsupper end and guided by means of an apertured transverse web portion 3.A spring 4 centered at its upper and lower ends as indicated in Figure 1constantly urges the stationary contact I downwardly. The stationcontactI is connected by means of a ilexible leader 5 with one arm of aU-shaped, bi-metallic thermostatic member 6, the other arm of which isconnected to a terminal 1'.

The movable contact 2 is carried in any suitable manner as by means ofthe switch operating member 8 and is connected by means of a flexibleleader 9 with a terminal in.

In the form of the invention chosen for illustration the switchoperating member 8 is an insulating bar provided with a slot H at itslefthand end as viewed in Figure 1 and is pivoted intermediate its endson the pivot pin l 2.

It is to be noted that the circuit breaker may be provided with aninsulating base portion l3 from which a pair of upwardly extendingwalls, also of insulating material, i4 project. These insulating wallsmay be joined by means of a transverse web portion l5 which carries thestationary contact i and the thermostatic member 6.

A carrier i6 is pivoted on the pivot pin I1 and is provided with a camportion or face ll adjacent its outer end and terminates in a hook likeportion [9. A latch member is pivoted on the pin 21 and is urged bymeans of the spring 22 towards a counterclockwise position. It isprovided with a transverse portion 23 behind which the extreme end IQ ofthe carrier 18 is normally latched. It is to be noted that the lowerface of the portion 23 is rounded as indicated at 24 to constitute a camsurface. It is also to be noted that the outer face adjacent the extremeend of the carrier it as indicated at 25 is slanting to provide a camsurface so that when the carrier is rocked towards latched position fromthe unlatched position shown in Figure 3 in a manner hereinafterdescribed, the surface II will ride beneath the surface 24 until thelatch snaps into place and locks the carrier in the position shown inFigure l.

Any suitable type of condition responsive means may be provided fortripping the latch. In the form shown in Figures 1, 2, 3 and 4 thebi-metallic thermostatic member 6 is employed to trip the latch. Thismember carries an insulating pad 38 at its outer end and the pad carriesan adjusting screw 21 which is adapted to bear against a transverse webportion 28 of the latch 20 so that when the thermostatic member 8 warpsdownwardly as viewed in Figure 1 upon overload, it will trip the latchand release the carrier II.

An actuator 23 is pivoted to the carrier by means of the pivot pin 30adjacent its upper end and is provided with a pin and roller 3!, 32which rides within the slot H. The actuator may consist of a pair ofarms located on opposite sides of the carrier I8 and the roller 32 maybe positioned between the arms. Each arm is provided with an offsetapertured ear 33v into which the lower end of tension springs 34 arehooked. The upper end of the tension springs 3| are secured to atransverse pin 35 carried by a main operating means in the form of apair of levers 36 pivoted at their lower ends on the pivot pin 31. Theupper ends oi the levers or main operating means 38 are joined by meansof a transverse pin 38 which may be connected by means of links 39 torock arms 40.

When the circuit breaker is mounted within a transformer casing ll asshown in Figure 6, it may be mounted directly upon the upper end of thetransformer indicated generally at 2. The rock arms 40 are carried bymeans 01 a rock shaft 43, one end of which projects out of thetransformer casing and is provided with an operating handle 44. Ifdesired, a stop 45 may be provided for limiting the closing motion ofthe handle.

It is to be noted that the pivot pin I1 is mounted almost directly belowthe pivot pin 30, which latter joins the actuator 29 to an intermediateportion of the carrier It. In this way the upward direct pull of thesprings though it is transmitted to the carrier does not have anyappreciable eiIect in increasing the contact pressure between theextreme hook portion IQ of the actuator and the latch 20. However, it isto be noted also that the position of the ears 33 with reference to thepivot pin 3| is such that the actuator constitutes a bell crank leverhaving a relatively short effective arm to which the springs 34 areattached and a relatively longer arm, namely, the main body portion ofthe actuator, to which the carrier is pivotally attached. In this waysubstantially the entire force biasing the carrier towards openposition, as shown in Figure 3, is that due to the bell crank action ofthe actuator and is not primarily due to the direct pull of the springs34. The dot and dash line 46, see Figure 1, shows the path followed bythe pin 30 when the carrier I 8 is released and it will be seen thatthere is scarcely any rise of the pin 30 from its normal position shownin Figure 1 when it travels along the are 48. Consequently it isimmediately seen that, as stated above, the direct upward pull of thesprings 34 produces at most only an extremely slight pressure of theactuator against the latch 20 and thus minimizes friction.

In certain prior constructions it has been the practice to have thedirect pull of springs corresponding to the springs 34 transmitteddirectly to th actuator and through the actuator directly to the latch.Considerable friction occurred and consequently a relatively large forcehad to be exerted to release the latch. However, by means of theconstruction hereinabove set forth, it is apparent that friction isminimized at the latch and only a. very small force is required torelease the latch. As a matter of fact, varying the relative distance ofthe ears 33 from the center of the pin 3| and the length of the othereffective arm of the actuator from the pin 3lto the pin 30 willdetermine the amount of pressure exerted by the actuator upon-the latch20.

Upon a further examination of Figure 1 it is to be noted that a peculiaraction takes place. The spring 34 keeps the pin 3| from moving to theright when the parts are in the position shown in Figure l and thethrust on the pin 30 urging the actuator towards counterclockwise motionis much smaller than the pull of the springs towards the left whichtends to hold the pin at the extreme left-hand end of the slot ll.

When it is desired to manually open th circuit breaker, the mainoperating means 36 is rocked .in a clockwise direction to the positionshown in Figure 2 and carries the line of pull of the springs 34 to theright of the pin 30. The actuator is consequently given an extremelyquick counterclockwise rotary motion and suddenly opens the circuitbreaker. When it is desired to close the circuit breaker, the mainoperating means 35 is rocked from the position shown in Figure 2 to theposition shown in Figure 1 and the line of pull of the springs 34 passesto the left of the pin 30 and consequently the actuator closes thecircuit breaker with a quick action.

When overload occurs, the condition responsive means, such as the.bi-metallic thermostatic member 6, warps downwardly and trips the latch20, thus releasing the carrier IS. The carrier i6 is biased towardscounterclockwise motion in the manner hereinabove described and rocks tothe position shown in Figure 3, thus carrying the pin 30 from theright-hand side of the line of pull of the springs 34, see Figure 1, tothe lefthand side thereof so that the actuator is caused to execute aquick counterclockwise motion to thus open the circuit breaker with aquick motion, The speed of opening of the circuit breaker is notdependent upon the speed of motion of the carrier but is dependent uponthe speed of motion of the actuator. This actuator may be made verylight and the springs 34 may be made sufficiently strong to cause theactuator to execute an extremely quick motion to open the circuitbreaker.

It is to be noted that in both manual operation and automatic operationthe same actuator is employed to operate the switch operating means 8.It is also to be noted from reference to Figure 1 that th actuator 29rocks slightly past center and thus locks the circuit breaker closed.

It is to be noted from reference to FigureZ that the pin 35 engages thecam surface [8 of the carrier l6 and thus acts to limit the clockwiserotation of the main operating means 36. If desired, a pin not shown maybe carried by the walls I4 to limit the counterclockwise motion of themain operating means 36 or if desired th stop 45, see Figure 7, may beemployed for this purpose.

After the circuit breaker has been automatically tripped, it is resetby.rocking the main operating means 36 to the right from the positionshown in Figure 3. Upon examination of Figure 3 it will be seen that thepin 35 engages the cam surface it of the carrier l6 and rocks thecarrier to the position shown in Figure 2. If the thermostatic element 6has cooled sufficiently, latching will occur, the cam surface 25 of thecarrier l6 riding beneath the cam surface 24 of the latch 20. On theother hand, if the thermostatic element has not cooled sufficiently,latching will not occur and no jamming or binding of the parts can occuras the latch is merely held clear of the portion I! of the carrier l6.

After the carrier has been relatched following an overload, the circuitbreaker is closed by rocking the main operating means 38 from theposition shown in Figure 2 to the position shown in Figure 1.

It is to be distinctly understood that if desired the pivot pin I! may'be mounted directly beneath the pivot pin 30 or may be mounted slightlyto the left of the pivot pin 30 as shown in Figure 1.

It will be seen that a circuit breaker has been provided which has aquick opening stroke whether manually or automatically opened and whichhas a quick closing stroke when manually closed. It will also be seenthat heavy contact pressure is provided though the circuit breaker maybe operated by means of a relatively small force and that this heavycontact pressure is maintained up to the instant that the circuitbreaker is quickly opened either automatically or manually.

If the circuit breaker.is mounted in the manner shown in Figure 6, itmay be mounted below the oil level indicated by the line 41. Under theseconditions the thermostatic member may be heated not only by the currentpassing therethrough but also by the general heat of the oil. Thepurpose of this is to allow the thermostatic element to respond not onlyto a relatively sudden overload but to allow it to respond to thegradual rise of temperature of the oil which would result from a smalland prolonged overload due to the heating of the transformer itself.Thus there may be afforded the double protection of opening the circuitbreaker under the influence of an overload of reasonable magnitude orthe opening of the circuit breaker from a prolonged small overload dueto the heating of the transformer. It is obvious also that if desiredthe main current need not pass through the thermal member and thethermal member could then respond merely to the heat of the oil or theoil level could be so regulated that it is below the thermal member andthen the thermal member would respond merely to the heat of the currentpassing therethrough.

The circuit breaker may be mounted in any suitable manner as hereinabovestated. For example, it may be arranged for wall mounting. In that eventthe circuit breaker is mounted within a casing or box 48 which may beprovided with a slotted rounded portion 49 through which a handle 36,which may be of insufating material, may project, the handle beingdirectly carried by the main operating means 36 hereinbefore described.

Referring to the wiring diagram shown in Figure 9, it will be seen thatthe secondary 50 of the transformer 42 may be connected to one arm ofthe bi-metailic thermostatic member 6. the

, 7. otherarmoiwhichisconnectedtothestaticnary contact 1.

Any suitable iorm oi condition responsive means may be employed. Forexample a solenoid type or condition responsive means may be employed asshown in Figure and may comprise the solenoid ii adapted to raise theplunger I! on overload. The plunger 52 is designed to rock the lever I!which carries the adjusting screw 21' corresponding to the screw 21hereinbeiore described, the screw 21' being adapted to trip the latch aspreviously described.

Any suitable time delay means may be provided. For example, the plunger52 may be provided with a piston 54 which is mounted within the'cylinder55, such cylinder being provided with apertures for the flow oi fluid. Asuitable spring 56 is provided for returning the plunger to its lowestposition.

It is apparent that the value or the condition to which the circuitbreaker may respond may be determined by the setting of the adjustingscrew 21 of Figure 1 and 21' of Figure 10.

The purpose of the time delay means such as shown for instance in Figure10 is to prevent the circuit breaker from suddenly opening for anysudden or extremely transitory overload for instance, but to allow thecircuit breaker to open as promptly as desired for an overload tor aperiod longer than that for which the circuit breaker is desi ned.

Other time delay means could, oi course, be employed and it is to bedistinctly understood that the circuit breaker could be made to respondto over or under voltage, overload, phase reversal, or any other desiredcondition.

It is to be understood that the circuit breaker may be mounted in anydesired position and reierences hereinabove to a pivot point beingpositioned below another pivot point are not intended as limiting butare merely intended to give the relative position of the parts.

It will be seen that a circuit breaker has been provided which is ofextremely simple construction, in which the same actuator is employedfor operating the switch operating means whether the circuit breaker isoperated manually or auto matically. It will be seen further that verylittle force is required to be exerted by the condition responsive meansas friction has been minimized by preventing a heavy pressure on thelatching parts due to the direct pull of the spring means, but insteadthe biasing action due to the spring means is transmitted through thebell crank construction of the actuator so that the force exerted at thelatch means is greatly minimized and may be predetermined and may be ofany value desired, depending on the design of the apparatus.

The circuit breaker chosen for illustration is a single switch unit typebut obviously as hereinbeiore stated the circuit breaker may be either asingle or a multiple switch type without departing from the spirit ofthis invention.

Although this invention has been described in considerable detail, it isto be understood that such description is intended as illustrativerather than limiting, as the invention may be variously embodied and isto be interpreted as claimed.

I claim:

1. A circuit breaker comprising switch means and switch operating meansfor opening and closing the switch means, a pivoted carrier, an actuatorhaving one end pivoted to said carrier and having a free end slidablyengaging said switch operating means, movable main operat- 8 ing means.over center spring means operativelyoonneciingsaidmainoperatingmeanstoapointonsaidactuatorspaoedlaterallyirom theelectiveaxisoisaidacuatorinadirectionawayirom the point about which saidcarrier is pivoted, said actuator constituting a bell crank leverbiasing said carrier towards motion due to the bell crank action oi saidactuator, and condition responsive means normally restraining saidcarrier against motion and releasing said carrier upon the occurrence oia predetermined condition, said carrier when said circuit breaker isclosed and when said carrier is released moving the pivot point of saidactuator across the line 0! pull 0! said spring means.

2. A circuit breaker comprising switch means and switch operating meansfor opening and closing the switch means, a pivoted carrier, an actuatorhaving one end pivoted to said carrier and having a free end slidablyeng ing said switch operating means, movable main operating means,spring means operatively connecting said main operating means andsaid-actuator and coacting with said actuator to bias said actuatortowards rotation about its free end to thereby bias said carrier towardsrocking motion, said actuator being arranged to normally exert a directthrust against said carrier substantially longitudinally of saidactuator and along a line passing approximately through the point aboutwhich said carrier is pivoted, said main operating means being adaptedto move said spring means to opposite sides oi the pivoted end of saidactuator to open and close said switch means, and condition responsivemeans releasably latching said carrier against motion.

3. A circuit breaker comprising switch means and switch operating meansfor opening and closing the switch means, a pivoted carrier, an actuatorhaving one end pivoted to said carrier and having a free end slidablyengaging said switch operating means, movable main operating means,spring means operatively connecting said main operating means and saidactuator and coacting with said actuator to bias said actuator towardsrotation about its free end to thereby bias said carrier towards rockingmotion, said main operating means being adapted to move said springmeans to opposite sides of the pivoted end of said actuator to open andclose said switch means. and condition responsive means releasablylatching said carrier against motion, said carrier when released by saidcondition responsive means being arranged to move the pivoted end oisaid actuator across the line of pull or said spring means.

4. A circuit breaker comprising switch means and switch operating meansfor opening and closing the switch means, a pivoted carrier. an actuatorhaving one end pivoted to said carrier and having a iree end slidablyengaging said switch operating means, movable main operating means,spring means operatively connecting said main operating means and saidactuator, said main operating means being adapted to move said springmeans to Opp site sides of the pivoted end of said actuator, said springmeans biasing said carrier towards rocking motion, the thrust from saidspring means through said actuator being applied to said carrierapproximately in line with the pivot point of said carrier when saidswitch means is closed and said carrier is in its normal position, andcondition responsive means releasably latching said carrier againstauaseo 5. A switch construction comprising switch means and switchoperating means for opening and closing said switch means. an actuatorhaving a pivoted end and having a free end slidably engaging said switchoperating means for actuating said switch operating means to open andclose said switch means, movable main operating means, spring meansoperatively connecting said main operating means with the free end ofsaid actuator, said main operating means being effective to move saidspring means to opposite sides of the pivoted end of said actuator, andmeans arranged to automatically move the pivoted end of said actuatoracross the line of pull of said spring means.

6. A switch construction comprising switch means and switch operatingmeans for opening and closing said switch means, an actuator havtowardsrotation about its free end to thereby bias said carrier towards rockingmotion, said main operating 'means being adapted to move said springmeans to opposite sides or the pivoted end of said actuator to open andclose said switch means, condition responsive means releasabiy ing apivoted end and having a free end slidably engaging said switchoperating means for actuating said switch operating means to open andclose said switch means. movable main operating means, spring meanshaving at least its major portion located on one side of said switchoperating means and operatively connecting said main operating meanswith the free end of said actuator, said main operating means beingeffective to move said spring means to opposite sides of the pivoted endof said actuator, a carrier pivoted on the side of said switch operatingmeans opposite said spring means and having an intermediate portionpivotally carrying said actuator at the pivoted end of said actuator,said intermediate portion being located on the same side of said switchoperating means as said spring means, said carrier being biased towardsrotary motion and arranged to carry the pivoted end of said actuatoracross the line of pull of said spring means, and latch means releasablyholding said carrier against motion.

7. A circuit breaker comprising switch means and switch operating meansfor opening and closing the switch means, a pivoted carrier, an actuatorhaving one end pivoted to said carrier and having a free end slidablyengaging said switch operating means, movable main operating means,spring means operatively connecting said main operating means and saidactuator and coacting with said actuator to bias said actuator towardsrotation about its free end to thereby bias said carrier towards rockingmotion, said actuator being arranged to normally exert a direct thrustagainst said carrier substantially longitudinally of said actuator andalong a line passing approximately through the point about which saidcarrier is pivoted, said main operating means being adapted to move saidspring means to opposite sides of the pivoted end of said actuator toopen and close said switch means, con dition responsive means releasablylatching said carrier against motion, and means operatively connectingsaid main operating means and said carrier to reset said carrier whensaid main operating means is moved to switch open position after releaseof said carrier by said condition responsive means.

8. A circuit breaker comprising switch means and switch operating meansfor opening and closing the switch means, a pivoted carrier, an actuatorhaving one end pivoted to said carrier and having a free end slidablyengaging said switch operating means, movable main operating means,spring means operatively connecting said main operating means and saidactuator and coacting with said actuator to bias said actuator latchingsaid carrier against motion, said carrier when released by saidcondition responsive means being arranged to move the pivoted end oisaid actuator across the line 0! pull of said spring means, and meansoperatively connecting said main operating means and said carrier toreset said carrier when said main operating means is moved to switchopen position after release of said carrier by said condition responsivemeans.

9. A circuit-breaker comprising switch means and switch operating meansfor opening and closing the switch means, a pivoted carrier, an actuatorhaving one end pivoted to said carrier and having a free end slidablyengaging said switch operating means, movable main operating means, overcenter spring means operatively connecting said main operating means toa point on said actuator spaced laterally from the effective axis ofsaid actuator in a direction away from the point about which saidcarrier is pivoted, said actuator constituting a bell crank leverbiasing said carrier towards motion due to the bell crank action of saidactuator, and condition responsive means normally restraining saidcarrier against motion and releasing said carrier upon the occurrence ofa predetermined condition, said carrier when said circuit breaker isclosed and when said carrier is released moving the pivot point of saidactuator across the line of pull of said spring means, said pivotedcarrier having a cam portion and said main operating means having aportion adapted to engage the cam portion to reset said carrier whensaid main operating means is moved to switch open position after releaseoi. said carrier by said condition responsive means.

10. A circuit breaker comprising switch means and switch operating meansfor opening and closing the switch means, a pivoted carrier, an actuatorhaving one end pivoted to said carrier and having a free end slidablyengaging said switch operating means, movable main operating means, overcenter spring means operatively connecting said main operating means toa point on said actuator spaced laterally from the effective axis ofsaid actuator in a direction away from the point about which saidcarrier is pivoted, said actuator constituting a bell crank leverbiasing said carrier towards motion due to the bell crank action of saidactuator, and condition responsive means including latch means normallyrestraining said carrier against motion and releasing said carrier uponthe occurrence 01 a predetermined condition, said carrier when saidcircuit breaker is closed and when said carrier is released moving thepivot point of said actuator across the line of pull of said springmeans, the pivot point of said carrier and the pivot point oi saidactuator being arranged with reference to said spring means so that themajor pressure exerted on said latch means by said carrier is dueprimarily to the bell crank action oi! said actuator and is relativelyfree from pressure due to the direct thrust from said spring means.

11. A circuit breaker comprising switch means and switch operating meansfor opening and closing the switch means, a pivoted carrier, an actuatorhaving one end pivoted to said carrier and having a free end slidablyengagin said mean 11 switch operating means. movable mainoperatdependent on the ing means, over center spring means operativelyconnecting said main operating means to a point on said actuator spacedlaterally from the e!- Iective axis of said actuator in a direction awayfrom the point about which said carrier is pivoted, said actuatorconstituting a bell crank lever biasing said carrier towards motion dueto the bell crank action of said actuator, and condition responsivemeans normally restraining said carrier against motion'and releasingsaid carrier upon the occurrence of a predetermined condition, saidcarrier when said circuit breaker is closed and when said carrier isreleased moving the pivot point of said actuator across the line 0! pullof said spring means, the speed of opening dependent oi. the speed orthe carrier and being 12 speed of operation of the HJW'INLLINK.

amass CITED The ioilowing references are of record in the iiie of thispatent:

UNITED STATES PATENTS actuator.

Number Name Date 2,071,843 Llndstrom Feb. 23, 198'! 2,195,016 SwingleMar. 28, i940 2,199,622 Dortman May "I, 1940 2,065,357 Von Boom Dec. 22,1936 FOREIGN PATENTS Number Country Date 683,106 German Oct. 30, 1939

